A new study by scientists from the University of Tsukuba, Japan, has found out that gut bacteria might help produce important chemical neurotransmitters, including dopamine and serotonin. This can affect normal sleep patterns and aid in good sleep.
Published in Scientific Reports, this research would open up more options for those people with sleep-related issues, such as mental fog, chronic fatigue, and insomnia.
There were 25 male mice in the study. They were 8 weeks old and genetically identical. Scientists divided them into 2 separate groups.
Mice in the control group had access to water without antibiotics. Other mice in the experimental group were provided with water mixed with broad-spectrum antibiotics, which are often used for depleting gut microbiota in mice.
After 1 month, the results revealed that mice in the control group had 200 more intestinal metabolites than those that consumed antibiotic water.
This suggested that antibiotics completely closed the tryptophan-serotonin pathway. Thus, it indicated that gut microbes play an important role in converting tryptophan in food into serotonin.
Also, the microbiota-depleted mice lacked vitamin B6 metabolites. These elements help accelerate the generation of dopamine and serotonin.
Next, the scientists looked at the brain activity of these mice through EMG and EEG signals from implanted electrodes.
This step suggested that the mice with depleted microbiota had more non-REM sleep and REM at night, a period when they should be active.
Lastly, the study observed that the mice in the experimental group had more non-REM episodes during the daytime and more REM sleep episodes during day and night.
Overall, all findings indicate that microbiota-depleted mice tended to switch more between wake and sleep stages. Scientists think that these sleep issues might be associated with low levels of serotonin. However, more research is needed to confirm this link.
The limitation of this research is that the scientists might not ignore the direct influence of the antibiotic treatment on brain function. They suggest that future research should use germ-free mice to overcome this challenge.
Also, other studies might administrate several microbes and use controlled feeding to identify gut microbiota. This enables researchers to measure the individual impact of each microorganism on the sleep and wake cycle.
Some studies reveal that prebiotics, which helps improve the health of the intestinal microbiota, might improve human’s sleep quality. Also, prebiotic supplements might improve sleep-associated sleep issues in rats.
Further research should test whether these claims are true in humans.